What sort of bomb was it? If it was a nuclear bomb, it should have caused some fallout. (rain with radiation) But the severity of that depends on a) how much radiation the bomb blew into the atmoshpere, and b) how high up it was. I imagine that, if the bomb exploded high enough, the radiation would have been spread thin enough to not cause any damage.
Come to think of it, alpha-particles should be able to damage the ozone layer profoundly, I think. But I'm no expert.
